drm/i915: Fix use after free in logical_render_ring_init
authorTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fri, 16 Dec 2016 13:18:42 +0000 (13:18 +0000)
committerJani Nikula <jani.nikula@intel.com>
Tue, 20 Dec 2016 14:30:27 +0000 (16:30 +0200)
commitd8953c8326d87a337763ca547ad7db034a94ddb1
treec992f007daa44dbe82bbeb284f742e150647a131
parent1c4672ce4eeaeaadeea8adabaad21262b7172607
drm/i915: Fix use after free in logical_render_ring_init

Commit 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs
structure only for the enabled engines") introduced the
dynanically allocated engine instances and created an
potential use after free scenario in logical_render_ring_init
where lrc_destroy_wa_ctx_obj could be called after the engine
instance has been freed.

This can only happen during engine setup/init error handling
which luckily does not happen ever in practice.

Fix is to not call lrc_destroy_wa_ctx_obj since it would have
already been executed from the preceding engine cleanup.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs structure only for the enabled engines")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1481894322-2145-1-git-send-email-tvrtko.ursulin@linux.intel.com
(cherry picked from commit d038fc7e4fff14d6b026130007faef35cbf5e956)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
drivers/gpu/drm/i915/intel_lrc.c